Method for manufacturing a semiconductor device

ABSTRACT

A substrate processing method with an improved etch selectivity includes: a first operation for forming a film on a stepped structure having a top surface, a bottom surface, and a side surface connecting the top surface and the bottom surface, wherein a first atmosphere is set to reduce a mean free path of plasma ions and to cause the plasma ions to have no directionality; and a second operation for changing a bonding structure of a portion of the film, wherein a second atmosphere is set to cause the plasma ions to have directionality, wherein the first operation is repeated a plurality of times, the second operation is performed for a predetermined time period, the first operation and the second operation form a group cycle, and the group cycle is repeated by a plurality of times.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional Application No.62/827,713, filed on Apr. 1, 2019, in the United States Patent andTrademark Office, the disclosure of which is incorporated herein in itsentirety by reference.

BACKGROUND 1. Field

One or more embodiments relate to a method of manufacturing asemiconductor device, and more particularly, to a method ofmanufacturing a semiconductor device, which is capable of improving anetch selectivity of a film formed on a stepped structure.

2. Description of the Related Art

In a process for manufacturing a device in which a microcircuit isformed on a substrate, a technique for forming a thin film on astructure having steps is used. Particularly, high density integratedcircuits such as a three-dimensional semiconductor device include atrench structure or a stepped structure, and a thin film needs to beformed on a selected area of the structure.

SUMMARY

The present disclosure provides a substrate processing method of forminga deposition film having a high etch selectivity on a stepped structurehaving a high aspect ratio to pattern the film by an isotropic etchprocess without performing a lithography process.

The present disclosure provides a substrate processing method capable ofcontrolling a profile of a deposition film formed on a steppedstructure.

Additional aspects will be set forth in part in the description whichfollows and, in part, will be apparent from the description, or may belearned by practice of the presented embodiments.

According to an aspect of embodiments based on a technical concept ofthe disclosure, a substrate processing method includes: a firstoperation for forming a film on a stepped structure having a topsurface, a bottom surface, and a side surface connecting the top surfaceand the bottom surface, wherein a first atmosphere is set to reduce amean free path of plasma ions and to cause the plasma ions to have nodirectionality; and a second operation for changing a bonding structureof a portion of the film, wherein a second atmosphere is set to causethe plasma ions to have directionality, wherein the first operation isrepeated a plurality of times, the second operation is performed for apredetermined time period, the first operation and the second operationform a group cycle, and the group cycle is repeated by a plurality oftimes.

According to an example of the substrate processing method, thesubstrate processing method may further include performing isotropicetching on a film formed by performing the group cycle a plurality oftimes.

According to another example of the substrate processing method, duringthe isotropic etching, an etch selectivity between the portion of thedeposition film whose bonding structure has changed and the otherportion of the deposition film may be achieved.

According to another example of the substrate processing method, in agroup cycle, the first operation may be performed m times, the secondoperation may be performed for n seconds, and a ratio of n to m may beadjusted to control a profile of a remaining film through the isotropicetching.

According to another example of the substrate processing method, duringthe second operation, the bonding structure of the portion of the filmmay be weakened by an ion bombardment effect of the plasma ions.

According to another example of the substrate processing method, theplasma ions may have directionality that is perpendicular to the topsurface and the bottom surface of the stepped structure, so that afterthe isotropic etching, a portion of the film formed on the top andbottom surfaces is removed and a portion of the film on the side surfaceremains.

According to another example of the substrate processing method,pressure in the first atmosphere may be higher than pressure in thesecond atmosphere.

According to another example of the substrate processing method, plasmapower in the first atmosphere may be lower than plasma power in thesecond atmosphere.

According to another example of the substrate processing method, atemperature in the first atmosphere may be higher than a temperature inthe second atmosphere.

According to another example of the substrate processing method, thefirst operation may include: supplying a first gas; purging the firstgas; and supplying a second gas and performing first plasma treatment toform the film.

According to another example of the substrate processing method, thesecond operation may include performing second plasma treatment on thefilm.

According to another aspect of embodiments based on a technical conceptof the disclosure, a substrate processing method includes: supplying afirst source gas; purging the first source gas; supplying a firstreaction gas and performing first plasma treatment to form a first film;supplying a second source gas onto the first film; purging the secondsource gas; supplying a second reaction gas and performing second plasmatreatment to form a second film on the first film; and performing thirdplasma treatment on at least a portion of the first film and the secondfilm, wherein the first film and the second film form a film includingthe same material.

According to an example of the substrate processing method, thesubstrate processing method may further include: supplying a thirdsource gas onto the second deposition film; supplying a third reactiongas and performing fourth plasma treatment to form a third film on thesecond film; and performing fifth plasma treatment on the third film,wherein the first film, the second film, and the third film form a filmincluding the same material.

According to another example of the substrate processing method, thefilm may be formed on a stepped structure having a top surface, a bottomsurface, and a side surface connecting the top surface and the bottomsurface, and a bonding structure of a portion of the film formed on thetop and bottom surfaces may be weakened by the third plasma treatmentand the fifth plasma treatment.

According to another example of the substrate processing method, thefirst plasma treatment, the second plasma treatment, and the fourthplasma treatment may be performed under first pressure, and the thirdplasma treatment and the fifth plasma treatment may be performed undersecond pressure that is lower than the first pressure.

According to another example of the substrate processing method, duringthe first plasma treatment, the second plasma treatment, and the fourthplasma treatment, a first power may be supplied, and during the thirdplasma treatment and the fifth plasma treatment, a second power than ishigher than the first power may be supplied.

According to another aspect of embodiments based on a technical conceptof the disclosure, a substrate processing method includes: performing agroup cycle a plurality of times, wherein the group cycle comprises: afirst operation for performing first plasma treatment to form a film ona stepped structure having a top surface, a bottom surface, and a sidesurface connecting the top surface and the bottom surface; and a secondoperation for performing second plasma treatment on the film, whereinduring a group cycle, the first operation is performed a plurality oftimes.

According to an example of the substrate processing method, during thefirst plasma treatment, pressure of a reaction space may be maintainedat first pressure, and during the second plasma treatment, pressure ofthe reaction space may be maintained at a second pressure that is lowerthan the first pressure.

According to another example of the substrate processing method, powerthat is supplied during the first plasma treatment may be lower thanpower that is supplied during the second plasma treatment.

According to another example of the substrate processing method, thesubstrate processing method may further include, after the group cycleis performed a plurality of times, performing isotropic etching toremove a portion of the film on the stepped structure to expose asurface of the stepped structure.

BRIEF DESCRIPTION OF THE DRAWINGS

These and/or other aspects will become apparent and more readilyappreciated from the following description of the embodiments, taken inconjunction with the accompanying drawings in which:

FIG. 1 is a flowchart schematically showing a substrate processingmethod according to embodiments based on a technical concept of thedisclosure;

FIGS. 2 and 3 schematically show substrate processing methods accordingto embodiments based on a technical concept of the disclosure;

FIG. 4 schematically shows a substrate processing method according toembodiments based on a technical concept of the disclosure;

FIG. 5 schematically shows a substrate processing method according toembodiments based on a technical concept of the disclosure;

FIG. 6 shows features that may occur in the substrate processing methodof FIG. 5;

FIGS. 7 and 8 schematically show substrate processing methods accordingto embodiments based on a technical concept of the disclosure;

FIG. 9 shows a state after the substrate processing method according tothe embodiments of FIGS. 7 and 8 is performed;

FIG. 10 shows states after thin films are deposited and wet etching isperformed according to various conditions;

FIG. 11 shows a state in which a profile of a thin film structure iscontrolled by changing conditions; and

FIG. 12 schematically shows a substrate processing method according toembodiments based on a technical concept of the disclosure.

DETAILED DESCRIPTION

Reference will now be made in detail to embodiments, examples of whichare illustrated in the accompanying drawings, wherein like referencenumerals refer to like elements throughout. In this regard, the presentembodiments may have different forms and should not be construed asbeing limited to the descriptions set forth herein. Accordingly, theembodiments are merely described below, by referring to the figures, toexplain aspects of the present description. As used herein, the term“and/or” includes any and all combinations of one or more of theassociated listed items. Expressions such as “at least one of,” whenpreceding a list of elements, modify the entire list of elements and donot modify the individual elements of the list.

Hereinafter, embodiments of the disclosure will be described withreference to the accompanying drawings.

The embodiments of the disclosure are provided to allow those havingordinary skill in the art to completely understand the disclosure. Theembodiments may, however, be embodied in many different forms, and thescope of the disclosure should not be construed as being limited to theembodiments set forth herein. Rather, these embodiments are provided sothat the disclosure will be thorough and complete, and will fully conveythe concept of the disclosure to one of ordinary skill in the art.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the disclosure.As used herein, the singular forms “a,” “an” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprises”and/or “comprising,” when used in this specification, specify thepresence of stated features, integers, steps, operations, elements,components, and/or groups thereof, but do not preclude the presence oraddition of one or more other features, integers, steps, operations,elements, components, and/or groups thereof. As used herein, the term“and/or” includes any and all combinations of one or more of theassociated listed items.

It will be understood that although the terms “first,” “second,” etc.may be used herein to describe various members, areas, layers, portions,and/or components, these members, areas, layers, portions, and/orcomponents should not be limited by these terms. These components do notindicate a specific order or superiority, but are only used todistinguish one member, area, layer, portion or component from another.Therefore, first members, areas, portions, or components may indicatesecond members, areas, portions, or components without departing fromteachings of the present disclosure.

In the present specification, the term “gas” may include an evaporatedsolid and/or liquid, and may be a single gas or a mixture of gases. Inthe present specification, a process gas introduced into a reactionchamber via a shower head may include a precursor gas and an additivegas. The precursor gas and the additive gas may be typically introducedinto a reaction space in the form of a mixed gas or may be independentlyintroduced into the reaction space. The precursor gas may be introducedtogether with a carrier gas, such as an inert gas. The additive gas mayinclude a reactant gas and a dilute gas, such as an inert gas. Thereactant gas and the dilute gas may be mixed and introduced into thereaction space, or may be independently introduced into the reactionspace. A precursor may include two or more precursors, and a reactantgas may include two or more reactant gases. The precursor is a gaschemisorbed onto a substrate and typically containing metalloid or metalatoms that form a major structure of a matrix of a dielectric film, andthe reactant gas for deposition is a gas that reacts with the precursorchemisorbed onto the substrate when the gas is excited to form an atomiclayer or a monolayer onto the substrate. “Chemisorption” refers tochemically-saturated adsorption. A gas other than the process gas,namely, a gas introduced, other than via the shower head, may be used toseal the reaction space. The gas includes a seal gas, such as an inertgas. According to some embodiments, a “film” refers to a layer thatcontinuously extends in a direction perpendicular to a thicknessdirection without pin holes in order to cover the entire area of atarget or a partial surface related to the target, or a layer thatsimply covers the target or the partial surface related with the target.According to some embodiments, a “layer” refers to a structure having acertain thickness formed on a surface, a film-type layer, or a non-filmstructure. A film or layer may be a single discontinuous film or layerhaving certain characteristics or may include multiple films or layers.A boundary between adjacent films or layers may be clear or unclear andmay be set based on physical characteristics, chemical characteristics,and/or other types of characteristics, forming processes or a formingsequence, and/or functions or purposes of adjacent films or layers.

In the present specification, a phrase “containing a Si—N bond” may becharacterized by a Si—N bond or Si—N bonds which may have a main framesubstantially formed by a Si—N bond or Si—N bonds and/or a substituentsubstantially formed by a Si—N bond or Si—N bonds. A silicon nitridelayer may be a dielectric layer containing a Si—N bond and may include asilicon nitride layer (SiN) and a silicon oxynitride layer (SiON).

In the present specification, the term “the same material” should beinterpreted as including the same main constituent. For example, when afirst layer and a second layer are both silicon nitride layers and areformed of the same material, the first layer may be selected from thegroup consisting of Si₂N, SiN, Si₃N₄, and Si₂N₃ and the second layer mayalso be selected from the same group, but in detail, a film material ofthe second layer may be different from that of the first layer.

In addition, in the present specification, an executable range may bedetermined based on a routine operation, two parameters may constitutean executable range, and an indicated range may include or exclude endpoints. In addition, values of some indicated parameters (regardless ofwhether or not the values are indicated by “about”) may refer toaccurate values or approximate values, and may include equivalentsthereof. According to some embodiments, the values of some indicatedparameters may refer to an average value, a center value, arepresentative value, a multi value, and the like.

In the present specification, when conditions and/or structures are notspecified, one of ordinary skill in the art may easily provide theseconditions and/or structures as an issue of a customary experiment. Inall disclosed embodiments, a component used in one embodiment includescomponents disclosed explicitly, necessarily, or intrinsically hereinfor intended purposes, and thus may be replaced by any of componentsequivalent to the component. Furthermore, the present disclosure isequally applicable to devices and methods.

Hereinafter, embodiments according to a technical concept of thedisclosure will be described with reference to the drawings. In thedrawings, variations from the shapes of the illustrations as a result,for example, of manufacturing techniques and/or tolerances, are to beexpected. Thus, the embodiments of the disclosure should not beconstrued as being limited to the particular shapes of regionsillustrated herein but are to include deviations in shapes that result,for example, from manufacturing.

FIG. 1 is a flowchart schematically showing a substrate processingmethod according to embodiments based on a technical concept of thedisclosure.

Referring to FIG. 1, a film may be formed in a first atmosphere, in afirst operation S110. The film may be formed on a stepped structure.That is, the film may be formed on a stepped structure having a topsurface, a bottom surface, and a side surface connecting the top surfaceand the bottom surface. The stepped structure may be a structure with ahigh aspect ratio, and the aspect ratio may be, for example,width:height=1:10 or more. To form a conformal deposition film on thestepped structure having the high aspect ratio, an atomic layerdeposition (ALD) process may be used. More specifically, a plasma atomiclayer deposition (PEALD) process may be used.

The first atmosphere in which the deposition film is formed may be setsuch that a mean free path of plasma ions is reduced and the plasma ionshave no directionality (that is, such that random movements of theplasma ions increase). The first atmosphere may contribute to formingthe conformal deposition film on the stepped structure having the highaspect ratio. To achieve the first atmosphere, a high-pressure (forexample, 10 Torr to 20 Torr) atmosphere may be created. According toanother embodiment, to achieve the first atmosphere, a low-poweratmosphere (for example, 200 W to 500 W) may be created. According tostill another embodiment, to achieve the first atmosphere, ahigh-temperature atmosphere may be created.

The first operation S110 of forming the film on the stepped structuremay include an operation of performing first plasma treatment. Morespecifically, the first operation S110 may include an operation ofsupplying a first gas, an operation of purging the first gas, anoperation of supplying a second gas, an operation of performing firstplasma treatment, and an operation of purging the second gas. While thefirst plasma treatment is performed, the second gas may be excited, andthe second gas having reactivity may react with the first gas to formthe film.

The first gas, which is a source gas, may include a material that ischemisorbed on a substrate. The second gas may include a material havingreactivity with the first gas, particularly, a material havingreactivity with the first gas under a plasma atmosphere. According to aselective embodiment, the operation of supplying the second gas and theoperation of performing the first plasma treatment may be performedsimultaneously.

The operation (that is, the first operation S110) of forming the film onthe stepped structure under the first atmosphere may be performed aplurality of times (for example, M times). More specifically, a groupcycle GC may be performed a plurality of times to deposit a film, andduring each group cycle GC, the first operation S110 may be performed aplurality of times. The number of repetitions of the first operationS110 relates to a second atmosphere that is set in a subsequent secondoperation S120. In other words, the first operation S110 may beperformed repeatedly by a predetermined number of times (that is, Mtimes) to form a film of a thickness that is suitable for plasmatreatment which will be performed in the second atmosphere.

After the first operation S110 is performed a plurality of times, thesecond operation S120 of changing a bonding structure of a portion ofthe film may be performed. During the second operation S120, secondplasma treatment may be performed on the film to change a bondingstructure of a portion of the film. It is noted that the second plasmatreatment during the second operation S120 is different from the firstplasma treatment that has been performed during the first operationS110. The second operation S120 may be performed in the secondatmosphere, and the second atmosphere may be set such that plasma ionshave directionality. In contrast, the first operation S110 may beperformed in the first atmosphere, and the first atmosphere may be setsuch that plasma ions have no directionality.

The plasma ions having directionality, which are supplied during thesecond operation S120, may change a bonding structure of a portion ofthe film. For example, when a film is formed on a stepped structurehaving an aspect ratio, the directionality of plasma ions may be set tobe toward a top surface or a bottom surface of the stepped structure. Inthis case, the plasma ions may change the bonding structure of the filmformed on the top surface or the bottom surface of the steppedstructure. In contrast, the plasma ions with the directionality may havelittle influence on the bonding structure of the film formed on the sidesurface of the stepped structure.

The change of the bonding structure of the portion of the film, causedby the plasma ions, may be weakening (see FIG. 2) of the bondingstructure or densification (see FIG. 3) of the bonding structure.Hereinafter, embodiments of the disclosure will be described in moredetail assuming weakening of the bonding structure.

During the second operation S120, the bonding structure of the portionof film may be weakened by an ion bombardment effect of the plasma ions.More specifically, the plasma ions may have directionality that isperpendicular to the top surface and the bottom surface of the steppedstructure. Accordingly, the bonding structure of the top surface and thebottom surface of the film may be weakened. As a result, in a subsequentisotropic etching operation S140, the film formed on the top and bottomsurfaces of the stepped structure may be removed, and the film formed onthe side surface of the stepped structure may remain.

During the second operation S120, a gas of the same material as thesecond gas (for example, a reaction gas) supplied in the first operationS110 may be supplied. A gas supply condition in the second operationS120 may be different from that in the first operation S110. Forexample, nitrogen may be supplied as a reaction gas during the firstoperation S110 and the second operation S120. In this case, the amountof a nitrogen gas supplied in the second operation S120 may be less thanthat supplied in the first operation S110. Also, the temperature of thenitrogen gas supplied in the second operation S120 may be lower thanthat supplied in the first operation S110. Also, plasma power applied tothe nitrogen gas supplied in the second operation S120 may be lower thanthat supplied in the first operation S110.

Under this supply conditions, as described above, in the first operationS110, random movements of the reaction gas (for example, a nitrogen gas)may increase to form a film of uniform quality in both horizontal andvertical directions, whereas in the second operation S120, thedirectionality of the reaction gas (for example, a nitrogen gas) mayincrease to change a bonding structure of the film (that is, the filmformed on the top and bottom surfaces of the stepped structure) in thevertical direction.

To increase the random movements of the reaction gas in the firstoperation S110, pressure of the reaction space may be maintained at afirst pressure (for example, high pressure) during the first plasmatreatment. In contrast, to cause the movements of the reaction gas tohave directionality in the second operation S120, pressure of thereaction space may be maintained at a second pressure (for example, lowpressure) that is lower than the first pressure, during the secondplasma treatment.

Also, to cause the reaction gas to be less influenced by power (that is,to cause the plasma ions to have no directionality) in the firstoperation S110, power that is supplied during the first plasma treatmentmay be maintained at a first power value (for example, a low powervalue). In contrast, to cause the reaction gas to be more influenced bypower (that is, to cause the plasma ions to have directionality) in thesecond operation S120, power that is supplied during the second plasmatreatment may be maintained at a second power value (for example, a highpower value) that is higher than the first power value.

In some alternative embodiments, to change the bonding structure of thedeposition film during the second operation S120, a gas (for example, ahydrogen-containing nitrogen gas) including hydrogen may be suppliedinto the reaction space. By performing plasma treatment by using the gasincluding hydrogen, more Si—H bonds may be formed in the film formed onthe top and bottom surfaces of the stepped structure, and therefore, awet etch rate (WER) may increase at the corresponding portions of thefilm during a subsequent etching processing.

The first operation S110 that is performed a plurality of times in thefirst atmosphere and the second operation S120 that is performed for apredetermined time period (for example, N seconds) in the secondatmosphere may be defined as a group cycle GC, and the group cycle GCmay be performed repeatedly. In other words, before a group cycle GC isperformed, an X value may be set to 1 in operation S100, and when agroup cycle GC including the first operation S110 and the secondoperation S120 is performed, the X value may increase in operation S150.When the X value reaches a predetermined value in operation S130, thegroup cycle GC may terminate and the subsequent isotropic etchingoperation S140 may be performed.

Thereafter, the isotropic etching operation S140 may be performed on afilm formed by performing the group cycle GC a plurality of times. Forexample, wet etching may be performed on the film. For example, wetetching of dipping a semiconductor device, that is, a substrate with athin film thereon, into a liquid etching solution to etch the surface ofthe substrate by a chemical reaction may be performed. Because the wetetching is isotropic etching, the isotropic etching may not greatlyaffect selective etching of the film formed on the stepped structure.

During the isotropic etching operation S140, an etch selectivity betweenthe portions of the film whose bonding structure has changed and theother portions of the film may be achieved. In other words, byperforming the second operation S120 of applying plasma to the filmafter the first operation S110 of forming the film on the steppedstructure, a bonding structure of some portions of the film on thestepped structure may change, and accordingly, during isotropic etching,some portions of the film may be removed and the other portions of thefilm may remain. Because some portions of the film on the steppedstructure are removed, the corresponding surface of the steppedstructure may be exposed. Accordingly, selective etching of thedeposition film may be achieved by a subsequent etching process.Therefore, a patterned film may be formed on an area of the steppedstructure without performing an additional photolithography process.

According to an alternative embodiment, in a group cycle GC, the firstoperation S110 may be performed M times, the second operation S120 maybe performed for N seconds, and a ratio of M and N may be adjusted tocontrol a profile of the remaining deposition film by isotropic etching.For example, by increasing an N value with respect to an M value, anetch selectivity between the film formed on the top and bottom surfacesof the stepped structure and the film formed on the side surface of thestepped structure may increase. By adjusting the etch selectivity, adegree by which the bottom surface of the stepped structure is exposedmay be adjusted (see FIG. 10). That is, by adjusting the M value and theN value, a profile of the deposition film remaining on the bottomsurface of the stepped structure may be finely adjusted.

As such, according to the embodiments based on the technical concept ofthe disclosure, instead of performing a first operation of forming afilm with a thickness of a nanometers on a stepped structure and asecond operation of performing plasma treatment on the film for bseconds once, the first operation and the second operation may form agroup cycle and the group cycle may be performed a plurality of times.In other words, a first operation of forming a film with a thickness ofc nanometers (c<a) on a stepped structure and a second operation ofperforming plasma treatment on the film for d seconds (d<b) may beperformed x times (x>1). Therefore, an etch selectivity between the filmformed on the top and bottom surfaces of the stepped structure and thefilm formed on the side surface of the stepped structure may beimproved.

FIGS. 2 and 3 schematically show substrate processing methods accordingto embodiments based on a technical concept of the disclosure. Thesubstrate processing methods according to the embodiments may bemodified examples of the substrate processing method according to theabove-described embodiments. Hereinafter, redundant descriptions aboutthe embodiments will be omitted.

Referring to FIG. 2, during the second operation S120 of performingplasma treatment on the deposition film, the bonding structure of thefilm may be weakened by plasma ions having directionality in the secondatmosphere. For example, by using a condition of low pressure and highplasma power, the bonding structure of the film formed on the top andbottom surfaces of the stepped structure may be weakened by an ionbombardment effect of active species. According to another example,hydrogen active species may be generated from the gas existing in thereaction space due to a reaction condition of the second atmosphere, andthe hydrogen active species may have directionality to collide with thefilm formed on the top and bottom surfaces of the stepped structure, sothat the bonding structure of the corresponding portions of thedeposition film may be weakened.

Accordingly, during the subsequent isotropic etching operation S140, theweakened portions (for example, the film formed on the top and bottomsurfaces of the stepped structure) of the film may be removed, and theother portions may remain, thereby achieving selective etching.According to some embodiments, to more stably perform the selectiveetching, a film having a first bonding structure (for example, a strongbonding structure) may be formed during the first operation S110.

In contrast with the embodiment of FIG. 2, during the second operationS120 of performing plasma treatment on the film, as shown in FIG. 3, thebonding structure of the film may be densified by plasma ions havingdirectionality in the second atmosphere. For example, plasma ions havingcomponents of the film may be provided to the film formed on the top andbottom surfaces of the stepped structure. As a concrete example, whenthe film is a thin film having Si—N bonds, nitrogen ions may be providedto the top and bottom surfaces of the stepped structure, andaccordingly, more Si—N bonds may be created so that the bondingstructure of the film may be densified.

Accordingly, during the subsequent isotropic etching operation S140, thedensified portions (for example, the film formed on the top and bottomsurfaces of the stepped structure) of the film may remain, and the otherportions may be removed, thereby achieving selective etching. Accordingto some embodiments, to more stably perform the selective etching, afilm having a second bonding structure (for example, a weak bondingstructure) may be formed during the first operation S110.

FIG. 4 schematically shows a substrate processing method according toembodiments based on a technical concept of the disclosure. Thesubstrate processing method according to the embodiments may be amodified example of the substrate processing method according to theabove-described embodiments. Hereinafter, redundant descriptions aboutthe embodiments will be omitted.

Referring to FIG. 4, X representing the number of times by which a groupcycle GC is performed may be set to an initial value of 1, in operationS100, and M representing the number of times by which the firstoperation S110 of forming the film is performed may also be set to aninitial value of 1, in operation S10. Then, the first operation S110that is performed M-th in a X-th group cycle may be performed. Duringthe first operation that is performed M-th (M=1), a first source gas maybe first supplied into a reaction space, in operation S11. The firstsource gas may be chemisorbed on a surface of a pattern structure (forexample, a stepped structure of a high aspect ratio (10:1 or more)) on asubstrate, and the first source gas remaining in the reaction space maybe purged and removed from the reaction space, in operation S12.Thereafter, a first reaction gas may be supplied into the reactionspace. After the first reaction gas is supplied (or, when the firstreaction gas is supplied), first plasma treatment may be performed toform a first film, in operation S13. Then, the first reaction gasremaining in the reaction space may be purged and removed from thereaction space, in operation S14.

Thereafter, M may increase (that is, M=2), and then, the first operationS110 which is performed M-th may be performed. That is, a second sourcegas may be supplied into the reaction space, in operation S11′, and thesecond source gas remaining in the reaction space may be purged andremoved from the reaction space, in operation S12′. Thereafter, a secondreaction gas may be supplied into the reaction space, and second plasmatreatment may be performed to form a second film, in operation S13′.Then, the second reaction gas remaining in the reaction space may bepurged and removed from the reaction space, in operation S14′.

As such, the first operation S110 may be repeated a plurality of times.The first operation S110 may be performed repeatedly until M reaches apredetermined value. While the first operation S110 is performedrepeatedly, the M value may continue to increase. A plurality of filmsformed by the first operation S110 performed a plurality of times mayform a film including the same material.

After a film of a desired thickness is formed by performing the firstoperation S110 by a predetermined number of times, the second operationS120 may be performed. During the second operation S120, third plasmatreatment may be performed on the formed film. As described above, thefirst atmosphere of the reaction space in which the first operation S110is performed may be different from the second atmosphere of the reactionspace in which the second operation S120 is performed.

By the third plasma treatment, a bonding structure of the film formed bythe first operation S110 may change (for example, weakening).Thereafter, a group cycle GC including the first operation S110 and thesecond operation S120 may be performed repeatedly. That is, the X valuemay increase to 2 from 1, the first operation S110′ may be againperformed M times, and then, the second operation S120′ may be againperformed.

For example, a second group cycle GC that is performed after the X valueincreases to 2 from 1 may further include operation S11″ of supplying athird source gas onto a second film, operation S12″ of purging the thirdsource gas, an operation S13″ of supplying a third reaction gas andperforming fourth plasma treatment to form a third film on the secondfilm, an operation S14″ of purging the third reaction gas, and anoperation S120′ of performing fifth plasma treatment on the third film.

The first film and the second film formed during the first operationS110 of the first group cycle GC and the third film formed during thefirst operation S110′ of the second group cycle GC may form a filmincluding the same material. The first operation may continue to beperformed to form a fourth deposition film. In another selectiveembodiment, the number of times by which the first operation isperformed during a group cycle may be different for each group cycle.

After the third film and/or the fourth film is formed, fifth plasmatreatment may be performed. By the fifth plasma treatment, a bondingstructure of the third film and/or the fourth film may change. In otherwords, by the third plasma treatment (operation S120) of the first groupcycle and the fifth plasma treatment (operation S120′) of the secondgroup cycle, a bonding structure of a portion of the deposition film maychange.

For example, when a silicon nitride film is formed on a steppedstructure having a top surface, a bottom surface, and a side surfaceconnecting the top surface and the bottom surface, plasma ions of strongpower may be injected into the film. Then, a Si—N bonding structure ofthe silicon nitride film may be broken. Because the plasma ions havedirectionality (vertical directionality toward a susceptor located belowfrom a shower head located above), the bonding structure of the filmformed on the top and bottom surfaces of the stepped structure may beweakened.

According to embodiments based on a technical concept of the disclosure,when a film of a predetermined thickness is formed, a portion of thefilm may be formed in some group cycles among a plurality of groupcycles, and the remaining portion of the film may be formed in theremaining group cycles. Also, plasma treatment may be performed on aportion of the film during each group cycle. As such, by repeatedlyperforming a group cycle for forming a portion of a film and performingplasma treatment on the portion of the film, instead of depositing afilm of a predetermined thickness and performing plasma treatment on theentire deposition film, an etch selectivity between the film formed onthe top and bottom surfaces of the stepped structure and the film formedon the side surface of the stepped structure may be improved.

According to some embodiments, during the first plasma treatment(operation S13) and the second plasma treatment (operation S13′) of thefirst group cycle and the fourth plasma treatment (operation S13″) ofthe second group cycle for forming the conformal deposition film, thefirst atmosphere of the reaction space may be set such that plasma ionshave no directionality. For example, the first plasma treatment(operation S13), the second plasma treatment (operation S13′), and thefourth plasma treatment (operation S13″) may be performed under firstpressure (that is, high pressure of, for example, 10 Torr to 20 Torr).As another example, during the first plasma treatment (operation S13),the second plasma treatment (operation S13′), and the fourth plasmatreatment (operation S13″), first power (that is, low power of, forexample, 200 W to 500 W) may be supplied.

In contrast, during the third plasma treatment (operation S120) of thefirst group cycle and the fifth plasma treatment (operation S120′) ofthe second group cycle, the second atmosphere of the reaction space maybe set such that the plasma ions have directionality. For example, thethird plasma treatment (operation S120) and the fifth plasma treatment(operation S120′) may be performed under second pressure (that is, lowpressure of, for example, 1 Torr to 5 Torr) that is lower than the firstpressure. As another example, during the third plasma treatment(operation S120) and the fifth plasma treatment (operation S120′),second power (that is, high power of, for example, 700 W to 1000 W) thatis higher than the first power may be supplied.

FIG. 5 schematically shows a substrate processing method according toembodiments based on a technical concept of the disclosure.

Referring to FIG. 5, the substrate processing method may include a firstoperation that is performed a plurality of times. In the firstoperation, a source gas (for example, a silicon source) may be suppliedfor t0 to t1, the remaining source gas may be purged for t1 to t3, areaction gas supplied to function as a purge gas and a reaction gas maybe excited by plasma application to react with the source gas to form afilm for t3 to t7, and the remaining reaction gas may be purged for t7to t8. The first operation may be performed repeatedly so that a film ofa predetermined thickness may be formed on a stepped structure.

For example, to deposit a SiN film on a stepped structure of asubstrate, a Si-containing precursor and a N2 gas may be supplied, andwhen plasma is supplied, the N2 gas may be ionized to react with theSi-containing precursor to form a thin film. Although the N2 gascontinues to be supplied, the N2 gas may be ionized under plasma tofunction as a reactive purge gas reacting with a source gas.

In the first operation, process pressure may be maintained at 3 Torr orlower and a power value may be maintained at 900 W or higher such that aconformal deposition film is formed and simultaneously, a portion of thefilm formed on the stepped structure is weakened. However, the processcondition may result in incomplete etching upon subsequent isotropicetching performed on the film formed on the stepped structure (see FIG.6).

(a) of FIG. 6 shows an example in which a film (for example, a SiN film)is lost in a part of a side portion of a step. (b) of FIG. 6 shows anexample in which a film (for example, a SiN film) is lost in a part of aside portion of a stepped structure having a great aspect ratio (forexample, an aspect ratio >10:1), and a film (for example, a SiN film)remains in a bottom portion of a step. (c) of FIG. 6 shows a case inwhich a film (for example, a SiN film) formed on a part of a sideportion of a step is lost and over-etch occurs in the inside (SiO₂ film)of a stepped structure in an etching operation after film deposition. Inthe case of (c) of FIG. 6, when a conductive material (for example, polySi) is filled in a subsequent process, an electrical short with theconductive material filled in the neighboring step may occur.

According to embodiments based on a technical concept of the disclosurefor preventing the incomplete selective etching, a first operation ofevenly depositing a firm and uniform film on a stepped structure and asecond operation of performing plasma treatment to increase an etchingselectivity of a film deposited on the side and top/bottom portions of astep may be performed.

FIGS. 7 and 8 schematically show a substrate processing method accordingto embodiments based on a technical concept of the disclosure. Thesubstrate processing method according to the embodiments may be amodified example of the substrate processing method according to theabove-described embodiments. Hereinafter, redundant descriptions aboutthe embodiments will be omitted.

The embodiments based on the technical concept of the disclosure proposea method of preventing loss of a film deposited on a side portion of astep. More specifically, a method of increasing a strength and chemicalresistance of a film to increase an etch selectivity between the filmdeposited on the top/bottom portion of a step and the film deposited onthe side portion of the step may be proposed to prevent the filmdeposited on the side portion of the step from being easily lost.

Referring to FIGS. 7 and 8, in a first operation (t0 to t8) which is anoperation of evenly depositing a hard and uniform film (for example, aSiN film) on a stepped structure, the film may be deposited by a PEALDprocess. The first operation may be performed repeatedly m times. Asecond operation (t8 to t15), which is a plasma treatment operation, maybe performed repeatedly for n seconds. A group cycle operationconsisting of the first operation and the second operation may beperformed repeatedly a plurality of times (for example, x cycles).

In the first operation, a hard and conformal film (for example, a SiNfilm) may be deposited on the stepped structure under conditions of highpressure (for example, 15 Torr) and relatively low plasma power (forexample, 500 watt). Because a large amount of gas exists (that is, highpressure) and plasma is relatively weak (that is, low power) in areaction space, a mean free path of radical ions may decrease and randommovements of the radical ions may increase. Accordingly, the ions may beevenly distributed on the top/bottom and side portions of the steppedstructure so that reactions between a substrate surface and ion radicalsoccur uniformly over the entire surface without being biased to acertain surface of a step, and therefore, a hard and uniform film(conformal film) may be deposited.

In the second operation, plasma may be supplied for a predetermined timeperiod under conditions of pressure that is relatively lower than in thefirst operation and plasma power that is relatively higher than in thefirst operation to increase an ion bombardment effect of plasma ions.For example, in the second operation, process pressure may be 3 Torr andplasma may be about 900 watt. To keep internal pressure of a chamber atlow pressure, reducing an amount of a reaction gas may be used asnecessary. Because directionality (straightness) of radical ions isreinforced, unlike the first operation, a bonding structure of a film(for example, a SiN film) deposited on a certain surface of the step,for example, on the top/bottom portion of the step, which isperpendicular to a traveling direction of radicals, may be weakened byion bombardment. The first operation and the second operation may form agroup cycle, and the group cycle may be performed repeatedly x times todeposit a desired film thickness. Thereafter, isotropic etching (forexample, wet etching) may be performed to remove the film formed on thetop/bottom surface of the stepped structure while maintaining the filmformed on the side wall.

Table 1 shows process conditions according to the embodiments based onthe technical concept of the disclosure, in detail.

TABLE 1 First Operation Second Operation (Conformal (Plasma Deposition)Treatment) Gas Flow Si Source 1000~2000 0 (sccm) (Carrier N2) N2(Reactive Purge) 10000~20000 1000~2000 Processing Source Supply0.15~0.7  0 Time Source Purge 0.5~1  0 (sec) Plasma 1~5  5~60 Purge0.1~0.3 0 Number of 10~50 — Times of Cycles Plasma Power (W) 200~500 700~1000 Frequency (Hz) 13.56M 13.56M Pressure (Torr) 10~20 1~5 HeaterTemperature (°C.) 300~550 300~550

In Table 1, comparing the first operation with the second operation, alarger amount of gas may be supplied at a rate of 5:1 to maximally 20:1in the first operation. By setting a supply time of plasma to 1:1 tomaximally 1:60, plasma power to 1:3.5 to maximally 1:5, and processpressure to 2:1 to maximally 20:1, the first operation may decrease amean free path of radical ions to deposit a uniform and hard film on thestepped structure, and the second operation may increase thestraightness and ion bombardment effect of the radical ions to weakenthe bonding structure of the film deposited on the top/bottom surface ofthe stepped structure. Accordingly, the film deposited on the sideportion of the step in the first operation may be hardened, therebybeing prevented from being lost in a subsequent etching operation.

FIG. 9 shows a result after the substrate processing method according tothe embodiments of FIGS. 7 and 8 is performed by depositing a SiN filmon a stepped structure and performing a subsequent etching processaccording to the process conditions shown in Table 1.

As shown in FIG. 9, the SiN film on the side wall of the step ismaintained at a constant thickness without being lost even at a boundarybetween the side wall and the bottom wall of the step, whereas the SiNfilm on the bottom surface of the step is selectively removed.

Furthermore, according to embodiments based on a technical concept ofthe disclosure, by changing a film material of the film formed on thetop and bottom portions of the step while maintaining a film material ofthe film on the side portion of the step, various forms of RTS (reversetopo-selective) process windows may be secured. More specifically, byadjusting a plasma processing condition of the second operation, a wetetch selectivity between the top/bottom portion of the step and the sideportion of the step may be arbitrarily adjusted, and a film profileafter etching may be adjusted.

As an example related to the adjustment of selectivity, Table 2 showsetch selectivities of the top and side surfaces of a step according tothe numbers of repetitions of the first operation and plasma treatmenttimes of the second operation. When the number of repetitions of thefirst operation is m (times) and the treatment time of the secondoperation is n (seconds), subsequent wet etching rates according tochanges of m and n are as follows.

TABLE 2 Conformal Treatment 1 Treatment 2 Deposition (m: 40 cy, (m: 20cy, (No treatment) n: 1 min) n: 1 min) Top Film WER 2.4 16.3 67 (A/sec)Side Film WER 2 2.4 2.6 (A/sec) Selectivity 1.2 6.8 25.8 (Top Portion/Side Portion WER)

In the Table 2, the conformal deposition condition represents a case inwhich the first operation is performed without the second operation. TheTreatment 1 condition (TRT1) represents a case in which the firstoperation is performed 40 times (40 cycles) and the second operation isperformed for 1 minute (60 seconds). The Treatment 2 condition (TRT2)represents a case in which the first operation is performed 20 times (20cycles) and the second operation is performed for 1 minute (60 seconds).

As shown in Table 2, as a ratio of the second operation to the firstoperation increases, a selectivity between the top portion and the sideportion in the stepped structure increases. That is, Table 2 shows thata highest WER selectivity of 25.8 is obtained under the Treatment 2condition. In other words, compared with the conformal depositioncondition, the SiN film on the top portion of the step is quicklyetched, whereas the SiN film on the side portion of the step is littleetched, under the Treatment 2 condition (TRT2). Therefore, a higher etchselectivity may be achieved.

FIG. 10 shows SiN films on steps after wet etching is performedaccording to the conditions (that is, the conformal depositioncondition, the Treatment 1 condition, and the Treatment 2 condition) ofTable 2.

Referring to FIG. 10, the conformal deposition condition represents acase in which the first operation is applied without the secondoperation to deposit a conformal SiN film in a stepped structure. In theconformal deposition condition, high process pressure and low plasmapower may be applied. Accordingly, radical ions may be evenlydistributed on the entire of the stepped structure, and even after wetetching, a hard SiN film of a constant thickness may remain evenly onthe top, side, and bottom portions of a step (see a left part of FIG.10).

Then, in the Treatment 1 condition (TRT1), the first operation may beperformed for 40 cycles, and then, plasma treatment of the secondoperation may be performed for 1 minute. As shown in the middle part ofFIG. 10, a SiN film formed on a side portion remains as it is, and a SiNfilm formed on a bottom portion is partially removed. However, in thebottom portion of the stepped structure, a SiN film may still remain.

Finally, under the Treatment 2 condition (TRT 2), the first operationmay be performed for 20 cycles, and then plasma treatment of the secondoperation may be performed for 1 minute. That is, by increasing a ratioof the second operation to the first operation, a SiN film formed on aside portion of a step is maintained with its original thickness withoutbeing lost, and a SiN film formed on a bottom portion of the step isremoved, after etching (see a right part of FIG. 10). As such, byappropriately adjusting a ratio of the first operation and the secondoperation, a substrate processing process with an improved thicknessadjustment function may be implemented.

FIG. 11 illustrates the process.

As shown in FIG. 11, by increasing a ratio of the second operation tothe first operation, a profile of a SiN film may be adjusted. Forexample, when the second operation is not performed (a left part of FIG.11), a SiN film formed on a bottom surface of a pattern PTN remains asit is even after isotropic etching. Meanwhile, when the second operationis performed at relatively low frequency (a middle part of FIG. 11), aSiN film formed on a bottom surface of a pattern PTN is partiallyremoved after isotropic etching so that a portion of the bottom surfaceof the pattern PTN is exposed. Also, when the second operation isperformed at relatively high frequency (a right part of FIG. 11), a SiNfilm formed on a bottom surface of a pattern PTN is completely removedafter isotropic etching so that the entire bottom surface of the patternPTN is exposed.

As such, a profile of a SiN film formed on bottom and side portions of astep may be controlled according to treatment times of a plasmatreatment operation. Accordingly, various shapes of thin film profilesmay be implemented according to application targets. For wiring oftop/bottom portions in a device, a bottom film formed on a step may beremoved. Also, by opening a portion of a bottom film, a device with moreimproved performance may be manufactured.

FIG. 12 schematically shows a substrate processing method according toembodiments based on a technical concept of the disclosure. Thesubstrate processing method according to the embodiments may be amodified example of the substrate processing method according to theabove-described embodiments. Hereinafter, redundant descriptions aboutthe embodiments will be omitted.

Referring to FIG. 12, the embodiments based on the technical concept ofthe disclosure propose a substrate processing method of processing asubstrate by performing a plurality of group cycles, and the substrateprocessing method may selectively etch a thin film on a pattern PTNthrough isotropic etching (for example, wet etching) without performingan additional photolithography process.

A group cycle may include a plurality of deposition cycles and plasmatreatment, and while the plurality of deposition cycles are performed, aconformal deposition film having a low subsequent wet etching rate WERmay be formed on a stepped structure. By performing strong plasmatreatment on the film formed after the plurality of deposition cycles, abonding structure of a portion of the film formed on the top and bottomportions of the stepped structure may change. The change of the bondingstructure may result in an increase of the subsequent wet etching rateWER.

After a group cycle terminates by performing the plurality of depositioncycles and strong plasma treatment, the next group cycle may beperformed so that a plurality of deposition cycles and strong plasmatreatment are again performed repeatedly. As such, a plurality of groupcycles may be performed to form a film with a predetermined thickness,in such a way to form a film and perform plasma treatment on a portionof the film in each group cycle, thereby forming a film with an improvedetch selectivity. As a result, a patterned film may be formed on astepped structure having a high aspect ratio, without performing alithography process.

It should be understood that embodiments described herein should beconsidered in a descriptive sense only and not for purposes oflimitation. Descriptions of features or aspects within each embodimentshould typically be considered as available for other similar featuresor aspects in other embodiments.

While one or more embodiments have been described with reference to thefigures, it will be understood by those of ordinary skill in the artthat various changes in form and details may be made therein withoutdeparting from the spirit and scope of the disclosure as defined by thefollowing claims.

What is claimed is:
 1. A substrate processing method comprising: a firstoperation for forming a film on a stepped structure having a topsurface, a bottom surface, and a side surface connecting the top surfaceand the bottom surface, wherein a first atmosphere is set to reduce amean free path of plasma ions and to cause the plasma ions to have nodirectionality; and a second operation for changing a bonding structureof a portion of the film, wherein a second atmosphere is set to causethe plasma ions to have directionality; wherein the first operation isrepeated a plurality of times, the second operation is performed for apredetermined time period, the first operation and the second operationform a group cycle, and the group cycle is repeated by a plurality oftimes.
 2. The substrate processing method of claim 1, further comprisingperforming isotropic etching on the film formed by performing the groupcycle a plurality of times.
 3. The substrate processing method of claim2, wherein, during the isotropic etching, an etch selectivity betweenthe portion of the film whose bonding structure has changed and theother remaining portion of the film is achieved.
 4. The substrateprocessing method of claim 2, wherein, in a group cycle, the firstoperation is performed m times, the second operation is performed for nseconds, and a ratio of n to m is adjusted to control a profile of aremaining film through the isotropic etching.
 5. The substrateprocessing method of claim 2, wherein, during the second operation, thebonding structure of the portion of the film is weakened by an ionbombardment effect of the plasma ions.
 6. The substrate processingmethod of claim 5, wherein the plasma ions have directionality that isperpendicular to the top surface and the bottom surface of the steppedstructure, so that after the isotropic etching, a portion of the filmformed on the top and bottom surfaces of the stepped structure isremoved and a portion of the film formed on the side surface of thestepped structure remains.
 7. The substrate processing method of claim1, wherein pressure in the first atmosphere is higher than pressure inthe second atmosphere.
 8. The substrate processing method of claim 1,wherein plasma power in the first atmosphere is lower than plasma powerin the second atmosphere.
 9. The substrate processing method of claim 1,wherein a temperature in the first atmosphere is higher than atemperature in the second atmosphere.
 10. The substrate processingmethod of claim 1, wherein the first operation comprises: supplying afirst gas; purging the first gas; and supplying a second gas andperforming first plasma treatment to form the film.
 11. The substrateprocessing method of claim 10, wherein the second operation comprisesperforming second plasma treatment on the film.
 12. A substrateprocessing method comprising: supplying a first source gas; purging thefirst source gas; supplying a first reaction gas and performing firstplasma treatment to form a first film; supplying a second source gasonto the first film; purging the second source gas; supplying a secondreaction gas and performing second plasma treatment to form a secondfilm on the first film; and performing third plasma treatment on atleast a portion of the first film and the second film, wherein the firstfilm and the second film comprise the same material.
 13. The substrateprocessing method of claim 12, further comprising: supplying a thirdsource gas onto the second film; supplying a third reaction gas andperforming fourth plasma treatment to form a third film on the secondfilm; and performing fifth plasma treatment on the third film, whereinthe first film, the second film, and the third film comprise the samematerial.
 14. The substrate processing method of claim 13, wherein thefilm is formed on a stepped structure having a top surface, a bottomsurface, and a side surface connecting the top surface and the bottomsurface, and a bonding structure of a portion of the film formed on thetop and bottom surfaces of the stepped structure is weakened by thethird plasma treatment and the fifth plasma treatment.
 15. The substrateprocessing method of claim 13, wherein the first plasma treatment, thesecond plasma treatment, and the fourth plasma treatment are performedunder first pressure, and the third plasma treatment and the fifthplasma treatment are performed under second pressure that is lower thanthe first pressure.
 16. The substrate processing method of claim 13,wherein, during the first plasma treatment, the second plasma treatment,and the fourth plasma treatment, first power is supplied, and during thethird plasma treatment and the fifth plasma treatment, second power thatis higher than the first power is supplied.
 17. A substrate processingmethod comprising: performing a group cycle a plurality of times,wherein the group cycle comprises: a first operation for performingfirst plasma treatment to form a film on a stepped structure having atop surface, a bottom surface, and a side surface connecting the topsurface and the bottom surface; and a second operation for performingsecond plasma treatment on the film, wherein, during a group cycle, thefirst operation is performed a plurality of times.
 18. The substrateprocessing method of claim 17, wherein, during the first plasmatreatment, pressure of a reaction space is maintained at a firstpressure, and during the second plasma treatment, pressure of thereaction space is maintained at a second pressure that is lower than thefirst pressure.
 19. The substrate processing method of claim 17, whereina power that is supplied during the first plasma treatment is lower thana power that is supplied during the second plasma treatment.
 20. Thesubstrate processing method of claim 17, further comprising, after thegroup cycle is performed a plurality of times, performing isotropicetching to remove a portion of the film on the stepped structure toexpose a surface of the stepped structure.